... years, tube and frame for 15 years1,vacuum tube length:47/1500mm,58/1800.2,vacuum tubes:15pcs,18pcs,20pcs,24pcs,30pcs3,Outer tank ... ,The high quality vacuum tubes ansorb the solar ultraviolet ray;then heat the cold water in the vacuum tube2,The hot water rise in the ... open its valve,the tap water flow in the tank ,if the water is full,it will close the valve automatically vacuum tube solar water heater